CN102260501A - Method for preparing red nano-fluorescent material - Google Patents

Abstract

The invention discloses a preparation method of a red nano fluorescent material. The material is prepared by using tetragonal tungsten bronze niobate as a matrix and doped with Eu ³⁺ . The preparation method is to mix Nb ₂ O ₅ and KOH, and keep it under the melting condition of 360-400°C for 10-60 minutes. The mixture was cooled to room temperature, dissolved in water and filtered, the filtrate was concentrated and crystallized, and then washed with a mixture of ethanol and water to obtain a soluble niobate precursor, which was then dissolved in water, and Gd(NO ₃ ) ₃ , Eu( NO ₃ ) ₃ and ethylenediaminetetraacetic acid mixed solution, after magnetic stirring at room temperature, KOH solution was added dropwise, and the pH value was controlled at 7-1. Put the solution into a reaction kettle, react at 140-200°C for 6-48 hours, and then cool to room temperature. The obtained precipitate can be washed, filtered, dried and roasted. The preparation method has simple process, cheap and easy-to-obtain raw materials, low energy consumption in the reaction process, and high environmental protection and high efficiency. The prepared fluorescent material has strong luminescence in the range of 595-630 nm, and can be used for solid-state light sources, lighting, laser diodes, and light energy converters. and display devices.

Description

A kind of preparation method of red nano fluorescent material

technical field

The invention relates to a preparation method of a red fluorescent material, in particular to a preparation method of a red rare earth-doped nano fluorescent material which can be used for a solid-state light source.

Background technique

Currently, lighting consumes approximately 20% of electricity generation in most countries. Therefore, research institutions are vigorously developing the next generation of high-efficiency and energy-saving solid-state light sources as the reserve army for lighting in this century. The commercialized solid white light source is a multi-color mixed light, which is generally prepared by mixing three primary color phosphors of red, green and blue. Therefore, the development of high-efficiency trichromatic phosphors is crucial to the development of solid-state light source technology. At present, the red phosphor powder based on GaN solid-state light source is Eu ²⁺ doped nitrogen silicate. This kind of red phosphor emits light mainly in the deep red region, and its lumen efficiency is low. Therefore, the low lumen efficiency and poor color reproduction of red phosphor become the bottleneck of the development of solid-state light source technology.

Compared with Eu ²⁺ -doped red phosphors, most Eu ³⁺ -doped nano-red phosphors have a luminous peak at around 610nm, and their luminous color reproduction is good, with high color purity and lumen efficiency. In addition, the Eu ³⁺ doped nano-red phosphor also has the characteristics of high physical and chemical stability and long fluorescence lifetime. Therefore, Eu ³⁺ doped nano red phosphor is expected to replace Eu ²⁺ doped nitrogen silicate. However, under near-ultraviolet or blue light excitation, the quantum efficiency of Eu ³⁺ doped nanomaterials is generally not high, so it is necessary to develop new high quantum efficiency Eu ³⁺ doped nano red phosphors.

Tungsten bronze niobate has a tetragonal symmetrical structure, high refractive index and good physical and chemical stability, and is a typical fluorescent host material. Because of its unique crystal structure, it can be replaced and doped with trivalent metal ions (including rare earth ions and transition group ions) to make it emit light of different colors. It can be predicted that such materials will have broad application prospects in many fields such as lighting, lasers, light energy converters and display devices.

Contents of the invention

The technical problem to be solved by the present invention is to provide a preparation method of red nano-fluorescent material. This preparation method uses tetragonal tungsten bronze niobate as the substrate and is doped with trivalent Eu ³⁺ to obtain red high-efficiency nano-fluorescent material. . The method uses niobium pentoxide as raw material, low-temperature synthesis, simple process, easy-to-obtain raw materials, high quantum efficiency and color purity under near-ultraviolet light excitation, and is expected to be used in solid-state light sources, lighting, lasers, light energy converters and Display equipment and other fields have obtained important applications.

The technical problem to be solved in the present invention is realized by following scheme: 1, a kind of preparation method of red nano fluorescent material, it is characterized in that: described fluorescent material is to be matrix with tetragonal tungsten bronze type niobate, trivalent Eu ³⁺ Doped and prepared, the preparation method is the following steps:

1) Mix Nb ₂ O ₅ and KOH according to the mass ratio w(Nb ₂ O ₅ ):w(KOH)=1:2~4, and keep it in a tube furnace under the melting condition of 360~400°C for 10~60 minutes;

2) cooling the above mixture to room temperature, dissolving in water and filtering, concentrating and crystallizing the filtrate, and washing with a mixture of ethanol and water with a volume ratio of 1:1 to obtain a soluble niobate precursor;

3) Take Gd ₂ O ₃ and Eu ₂ O ₃ and add dilute HNO ₃ to get Gd(NO ₃ ) ₃ , Eu(NO ₃ ) according to the ratio of substances n(Gd):n(Eu)=19～3:1 ₃ mixed solution A;

4) Take ethylenediaminetetraacetic acid and add it to deionized water, the addition ratio is n(ethylenediaminetetraacetic acid):V(H ₂ O)=0.0005～0.002mol:50ml, and then according to the amount of substances, the ratio is n(ethylenediaminetetraacetic acid) Ammonium tetraacetic acid): (n(Gd)+n(Eu))=0.5～2:1 is added to the mixed solution A to obtain a mixed solution of Gd(NO ₃ ) ₃ , Eu(NO ₃ ) ₃ and ethylenediamine tetraacetic acid B;

5) Take the above-mentioned niobate precursor and dissolve it in deionized water, and add the ratio of n(niobate):V(H ₂ O)=0.001～0.003mol:50ml, and then make n(niobate Salt):n(mixed solution B)=1～3:1 was added to mixed solution B, and magnetically stirred at room temperature for 10～60 minutes to become mixed solution C;

6) Add KOH solution dropwise to the mixed solution C, and control the pH value of the solution at 7-14;

7) Put the above solution into the reactor, react at 140-200°C for 6-48 hours, then cool to room temperature;

8) The precipitate obtained by the reaction is repeatedly washed with deionized water for 3 to 5 times, dried at 60 to 100°C for 2 to 6 hours, and calcined at 500 to 1000°C.

The precursor prepared by the above-mentioned mixture of Nb ₂ O ₅ and KOH can be replaced by niobium salts. At this time, roasting is not required, and it can be dissolved in a relevant solvent to form a solution. Niobium salts include niobium chloride, niobium ethoxide, etc., and related solvents refer to alcohols, such as methanol, ethanol, etc.

The red fluorescent nanometer material K ₂ GdNb ₅ O ₁₅ prepared by the preparation method has high dispersion, strong luminescence at 595-630 nm, and quantum efficiency of 80.9%.

The present invention has the following advantages:

1. Realized the effective doping of trivalent Eu ³⁺ into the niobate lattice, and obtained tetragonal tungsten bronze niobate as the matrix and Eu ³⁺ doped ions as the luminescence center with high quantum efficiency and high color purity. red nano fluorescent material.

2. The preparation process is simple, the operation is easy, the raw materials are cheap and easy to obtain, and it is suitable for industrial production; the reaction process has low energy consumption, and belongs to the industry of green environmental protection and high efficiency.

3. Luminescent materials are used in fields such as solid-state light sources, lighting, laser diodes, light energy converters, and display devices.

Description of drawings

Figure 1 is the XRD pattern of the red nano fluorescent material K ₂ GdNb ₅ O ₁₅ prepared by this method

(a-unroasted sample; b-roasted 1000°C sample)

Fig. 2 is the fluorescence spectrum diagram of the _red nano-fluorescent material _K2GdNb5O15 prepared by _this method

(a, b-excitation and emission spectra of uncalcined samples; c, d-excitation and emission spectra of samples calcined at 1000℃)

Detailed ways

Below by embodiment the present invention will be further described.

Example 1: Weigh 13.3g Nb ₂ O ₅ and 26g KOH into a crucible, bake at 400°C for 30 minutes; cool the above mixture to room temperature, dissolve it in water and filter, concentrate the filtrate to crystallize, and then use a mixture of ethanol and water (volume ratio 1:1) to obtain a soluble niobate precursor, and weighed 1.82g of niobate precursor dissolved in water; 0.168g of Gd ₂ O ₃ and 0.009g of Eu ₂ O ₃ dissolved in HNO ₃ solution, then add 0.12g of ethylenediaminetetraacetic acid; then add this mixed solution into the niobate solution, and stir magnetically at room temperature for 10 minutes; add KOH solution drop by drop, and adjust the pH value of the solution to 13; The above solution was then transferred into a polytetrafluoroethylene-lined reactor, kept at 200°C for 24 hours, and then cooled to room temperature; the precipitate obtained was taken out of the reactor, washed, filtered and dried.

The XRD pattern of the obtained sample (test conditions: voltage 40kV, current 40mA, scan speed 1°/min) shows that the crystallization of the sample is not complete, and the grain size is small (<2nm) (see Figure 1a).

The fluorescence spectrogram of the obtained sample (test conditions: λ _ex = 394nm, λ _em = 614nm, slit width 0.5nm, step length 1nm, integration time 0.3s) shows that: the fluorescent material has a strong intensity in the 300-460nm region. Absorption, strong fluorescence at 595-630nm (see Figure 2a and 2b), the internal quantum efficiency can reach 73.5%.

Example 2: Weigh 13.3g Nb ₂ O ₅ and 26g KOH into a crucible, bake at 400°C for 30 minutes; cool the above mixture to room temperature, dissolve it in water and filter, concentrate the filtrate to crystallize, and then use a mixture of ethanol and water (Volume ratio 1:1) to obtain a soluble niobate precursor, and weigh 1.82g of niobate precursor dissolved in water; 0.168g of Gd ₂ O ₃ and 0.009g of Eu ₂ O ₃ dissolved in HNO ₃ solution, then add 0.12 g of ethylenediaminetetraacetic acid; then add this mixed solution into the niobate solution, and stir magnetically at room temperature for 10 minutes; add KOH solution drop by drop, and adjust the pH value of the solution to 13; Then the above solution was moved into a polytetrafluoroethylene-lined reactor, kept at 200°C for 24 hours and then cooled to room temperature; the precipitate obtained was taken out of the reactor, washed, filtered and dried; then roasted in a roaster at 1000°C for 2 hours.

The XRD pattern of the obtained sample (test conditions: voltage 40kV, current 40mA, scan speed 1°/min) shows that the sample shows the characteristic peak of K ₂ GdNb ₅ O ₁₅ (see Figure 1b).

The fluorescence spectrogram of the obtained sample (test conditions: λ _ex = 394nm, λ _em = 614nm, slit width 0.5nm, step length 1nm, integration time 0.3s) shows that this fluorescent material also has a strong emission in the 300-460nm region. Absorption, strong fluorescence at 595-630nm. Compared with the unbaked sample, the fluorescence peak intensity of this sample is enhanced (see Figure 2c and 2d), and the internal quantum efficiency is also increased, up to 80.9%.

Example 3: Weigh 13.3g Nb ₂ O ₅ and 26g KOH into a crucible, bake at 400°C for 30 minutes; cool the above mixture to room temperature, dissolve it in water and filter, concentrate the filtrate to crystallize, and then use a mixture of ethanol and water (Volume ratio 1:1) to obtain a soluble niobate precursor, and weigh 1.82g of niobate precursor dissolved in water; 0.168g of Gd ₂ O ₃ and 0.009g of Eu ₂ O ₃ dissolved in HNO ₃ solution, then add 0.12g of ethylenediaminetetraacetic acid; then add this mixed solution into the niobate solution, and stir magnetically at room temperature for 10 minutes; add KOH solution drop by drop, and adjust the pH value of the solution to 9; The above solution was then transferred into a polytetrafluoroethylene reactor, kept at 140°C for 48 hours, and then cooled to room temperature; the precipitate obtained was taken out of the reactor, washed, filtered and dried.

Example 4: Weigh 13.3g Nb ₂ O ₅ and 26g KOH into a crucible, bake at 400°C for 30 minutes; cool the above mixture to room temperature, dissolve it in water and filter, concentrate the filtrate to crystallize, and then use a mixture of ethanol and water (Volume ratio 1:1) to obtain a soluble niobate precursor, and weigh 1.82g of niobate precursor dissolved in water; 0.168g of Gd ₂ O ₃ and 0.009g of Eu ₂ O ₃ dissolved in HNO ₃ solution, then add 0.6g of ethylenediaminetetraacetic acid; then add this mixed solution into the niobate solution, and stir magnetically at room temperature for 10 minutes; add KOH solution drop by drop, and adjust the pH value of the solution to 13; The above solution was then transferred into a polytetrafluoroethylene reactor, kept at 200° C. for 24 hours, and then cooled to room temperature; the precipitate obtained was taken out of the reactor, washed, filtered and dried.

Claims (1)

1. red nano Preparation of Fluorescent Material method is characterized in that: described fluorescent material is to be matrix with cubic tungsten bronze type niobate, trivalent Eu ³⁺Mix and make, the preparation method is following steps:

1) with Nb ₂O ₅Press mass ratio w (Nb with KOH ₂O ₅): mix w (KOH)=1: 2～4, kept 10～60 minutes under 360～400 ℃ of melting conditions in tube furnace;

2) said mixture is cooled to room temperature, water-soluble filtration with the filtrate condensing crystal, is that the mixed solution washing of 1: 1 second alcohol and water obtains solubility niobate precursor with volume ratio again;

3) get Gd ₂O ₃And Eu ₂O ₃Add rare HNO ₃, according to amount of substance than n (Gd): n (Eu)=19～3: 1 obtains Gd (NO ₃) ₃, Eu (NO ₃) ₃Mixed solution A;

4) get ethylenediamine tetraacetic acid (EDTA) and add in the deionized water, additional proportion is n (ethylenediamine tetraacetic acid (EDTA)): V (H ₂O)=and 0.0005～0.002mol: 50ml, be n (ethylenediamine tetraacetic acid (EDTA)) according to the amount of substance ratio again: (n (Gd)+n (Eu))=0.5～2: 1 adds in the mixed liquor A, obtains Gd (NO ₃) ₃, Eu (NO ₃) ₃And ethylenediamine tetraacetic acid (EDTA) mixing solutions B;

5) get above-mentioned niobate precursor and be dissolved in deionized water, additional proportion is n (niobate): V (H ₂O)=and 0.001～0.003mol: 50ml, be n (niobate): n (mixed liquid B)=1～3 according to the amount of substance ratio again: 1 adds in the mixed liquid B, and at room temperature magnetic agitation became mixed solution C in 10～60 minutes;

6) dropwise drip KOH solution in mixed solution C, the pH value of control solution is 7～14;

7) above-mentioned solution is put into reactor, behind 140～200 ℃ of following reaction 6～48h, be cooled to room temperature;

8) will react gained precipitate with deionized water repetitive scrubbing 3～5 times, drying is 2～6 hours under 60～100 ℃, and 500～1000 ℃ of following roastings.

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